Vitamin D deficiency as risk factor for severe COVID-19: a convergence of two pandemics

Structured abstractO_ST_ABSContextC_ST_ABSThrough its immunological functions, vitamin D attenuates inflammatory responses to respiratory viruses. Vitamin D deficiency might be a highly prevalent risk factor for severe SARS-CoV-2 infections. ObjectiveTo investigate the level of vitamin D deficiency in West Flanders, Belgium and its correlation to severity of COVID-19 as staged by CT DesignRetrospective observational study Setting. Central network hospital Participants186 SARS-CoV-2-infected patients hospitalized from March 1, 2020 to April 7, 2020 Main outcome measureAnalysis of 25(OH)D in COVID-19 patients versus season/age/sex-matched diseased controls ResultsThe rate of vitamin D deficiency (25(OH)D<20 ng/mL) in West Flanders varies with age, sex and season but is overall very high (39.9%) based on analysis of 16274 control samples. We measured 25(OH)D levels in 186 COVID-19 patients (109 males (median age 68 years, IQR 53-79) and 77 females (median age 71 years, IQR 65-74)) and 2717 age/season-matched controls (999 males (median age 69 years, IQR 53-81) and 1718 females (median age 68 years, IQR 43-83)). COVID-19 patients showed lower median 25(OH)D (18.6 ng/mL, IQR 12.6-25.3, versus 21.5 ng/mL, IQR 13.9-30.8; P=0.0016) and higher vitamin D deficiency rates (58.6% versus 45.2%, P=0.0005). Surprisingly, this difference was restricted to male COVID-19 patients who had markedly higher deficiency rates than male controls (67.0% versus 49.2%, P=0.0006) that increased with advancing radiological stage and were not confounded vitamin D-impacted comorbidities. Conclusionsvitamin D deficiency is a prevalent risk factor for severe COVID-19. Vitamin D supplementation might be an inexpensive and safe mitigation for the SARS-CoV-2 pandemic. O_TEXTBOXSUMMARY BOXO_ST_ABSWhat is already known on this topicC_ST_ABSVitamin D deficiency increases the incidence and severity of respiratory viral infections by exacerbation of pro-inflammatory immune responses. Lung damage in COVID-19 involves excessive inflammation and cytokine release. With more than 1 billion people worldwide affected by vitamin D deficiency the world might now face a convergence of two pandemics. Data are emerging that variations in vitamin D deficiency rates across ethnic and demographic subgroups are correlated to severity of SARS-CoV-2 infections. What this study addsOur data reveal that more than 40% of the adult population in a wealthy European country is vitamin D deficient. We show that vitamin D deficiency is correlated with the risk for hospitalization for COVID-19 pneumonia and predisposes to more advanced radiological disease stages. Specifically, men were at risk. This correlation was not confounded by vitamin D-impacted morbidities such as coronary artery disease, diabetes and chronic lung disease. Our findings support a causal relation between vitamin D deficiency and severe COVID-19 and call for vitamin D supplementation as safe, widely available and inexpensive mitigation strategy. C_TEXTBOX